ER-40 CAT 40 V-Flange Collet Chuck With 2.75 Gage Depth (3900-4028) ~ For CNC machines with a CAT 40 spindle taper. ~ Hardened and precision ground. ~ Drawbar end thread is 5/8″-11. ~ Collet range is 0.120-1.020″. ~ T.I.R. is <=.0002″. For CNC machines with a CAT 40 spindle taper. Hardened and precision ground. Drawbar end thread is 5/8″-11. Collet range is 0.120-1.020″. T.I.R. is <=.0002″.